Catheter to assist the performance of a heart

ABSTRACT

In a catheter ( 2 ) to assist the performance of a heart ( 1 ) with at least one pump ( 7 ), the pump is formed as a rotary pump at the distal end of the catheter ( 2 ), the rotor ( 6 ) lying distally on the outer side being coupled via a magneto coupling with a drive wheel ( 21 ), formed as a hydraulically or pneumatically operated paddle wheel, arranged inside the catheter ( 2 ). The driving fluid is supplied to the paddle wheel via a lumen ( 22 ) of the catheter ( 2 ) and is carried off via a further lumen ( 23 ) of the catheter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage application under 35 U.S.C. §371and claims benefit under 35 U.S.C. §119(a) of International ApplicationNo. PCT/IB2008/000421 filed on Feb. 27, 2008, which claims the benefitof Austrian Patent Application Serial No. A306/2007 filed on Feb. 27,2007, and the contents of these prior applications are herebyincorporated by reference.

FIELD Background

The invention relates to a catheter to assist the performance of a heartwith at least one pump.

After a heart failure, for example a cardiac infarction or other reasonsfor the decrease in the performance of a heart, it is of essentialimportance for intensive care medicine to normalise and stabilise thecardiac function again as rapidly as possible. When for example thevolume output of the heart is distinctly reduced as a result of afailure, it is particularly important to reliably and rapidlyre-establish a corresponding peripheral blood flow in order to preventsecondary damage. The use of heart-lung machines basically allows theessential vital functions to be maintained. A specific adaptation to therespective actual requirements generally does not take place with suchdevices, however. Rather, conventional heart-lung machines are deviceswhich, using external pumps, maintain a forced circulation of bloodwithout systematically entering into the respective requirements of theheart which has been weakened or subjected to a failure.

In surgical interventions, particularly in the vein area, it has alreadybeen proposed to carry out retroinfusion, controlled by venous pressure,from or in veins of the body with the suction of fluid and return of thefluid via a pump. Conventional catheters are used here, the lumina ofwhich allow a suction of fluid and via the lumina of which the return ismade possible at a suitable site. Known devices, particularly for theretroinfusion of blood in coronary veins in the area of myocardialprotection during a brief coronary artery closure within a cardiologicalintervention, are generally devised so that a balloon dilatation of anarteriosclerotically constricted coronary artery is carried out. Inthese cases, a compensation which is adapted to the intervention brieflytaking place respectively can be carried out by the return of bloodwhich has been drawn off in veins. For a continuous restitution of thefull function of a heart, however, the criteria are not taken intoaccount which would be relevant for the full function of the heart, andan intensive provision over a particular period of time is therefore notprovided with such devices. At the same time, the provision of the otherorgans must also be maintained.

In the device known from AT 407 960 B for assisting the performance of aheart, fluid is removed from blood vessels via an external pump and isreturned into blood vessels via a return catheter, in which the returnedquantity of fluid is regulated as a function of measurement values, witha heart ventricle catheter being provided to obtain these measurementvalues. The known device comprised a heart ventricle catheter which isequipped in the cardiac chamber with sensors to measure the volume offluid per unit of time, in which these sensors, in the introduced stateof the heart ventricle catheter, lie in the cardiac chamber and thesesensors are connected with an evaluation circuit in which the ratio ofthe diastolic volume to the systolic volume is evaluated per heartbeator per unit of time in particular the discharge rate and/or thedeviation of the volume conveyed per unit of time by the heart from adefined rated value is evaluated, for example the rated value,calculated from physically specific data for the cardiac output. Thesignal which is generated in this way is passed to the pump, via whichfluid is withdrawn from the cardiac chamber and is recirculated as afunction of the generated signal.

SUMMARY

The invention now aims to further develop this known device to theeffect that an external pump can be dispensed with and, at the sametime, the desired pressure increase can be brought into effectsystematically at particular locations. In particular, the fluid flowwhich is improved by the pump is to be developed in a way in which themechanical stress of highly sensitive fluids, such as blood for example,can be kept as low as possible and nevertheless the correspondingimprovement to circulation can be ensured at desired locations. To solvethis problem, the initially mentioned device of the catheter accordingto the invention, which can be used within the scope of the devicedescribed above, consists substantially in that the pump is constructedas a rotary pump at the distal end of the catheter, in which the rotorlying distally on the outside is coupled via a magneto coupling with adrive wheel which is arranged inside the catheter and is formed as apaddle wheel which is operated hydraulically or pneumatically and thedriving fluid is supplied to the paddle wheel via a lumen of thecatheter and is carried off via a further lumen of the catheter. Such anaxial pump, which is directly connected with the catheter, can bebrought with the catheter directly into the desired position and, at thesame time, can be used here with further therapeutic additions such as,for example, a retroperfusion through cyclic occlusion of the bloodvessel by means of a balloon. In order to guarantee a completeuncoupling from the driving medium driving the pump and in particular toensure that simple driving means such as, for example, hydraulically orpneumatically operated paddle wheels can be used, a completelyimpervious separation of the rotor from the drive wheel is achieved bythe magneto coupling which is provided according to the invention, whicheliminates axial passages between the drive wheel and the rotor lyingdistally on the outside. The embodiment is hereby devised according tothe invention so that the drive wheel is formed as a hydraulically orpneumatically operated paddle wheel, with the driving fluid beingsupplied to the paddle wheel via a lumen of the catheter and beingcarried off via a further lumen of the catheter, in which preferably thepaddle wheel is constructed with axial or semi-axial blades. Theoperation of such an arrangement can take place in a simple manner bymeans of correspondingly regulated hydraulic or pneumatic reservoirs,with the driving medium being supplied via corresponding regulatingvalves to the drive wheel which is coupled magnetically with the rotor.

The device is designed in a structurally particularly simple manner suchthat the axis of rotation of the rotor is in alignment with thelongitudinal axis of the catheter or is parallel thereto. A developmentof the catheter which has a correspondingly low wear and is impervious,with, at the same time, a secure mounting of the rotor, can be achievedin that the coupling is formed by bar magnets which, in adjacentchambers separated from each other hydraulically by a sealing wall, atthe distal end of the catheter are respectively connected with the rotorand with the drive wheel so as to be locked against relative rotation,in which preferably the connections, locked against relative rotation,of the drive wheel or of the rotor with the respective bar magnets arerespectively mounted in the walls of the chambers facing away from thesealing wall and facing the drive wheel or the rotor respectively.

The rotor itself can follow design principles such as described forexample in WO 01/70300 A1. The rotary pump shown and described there forconveying blood and other highly sensitive fluids is formed as anexternal electromagnetically driven pump which is not directly suitablefor incorporation into a catheter. The known design namely assumes thatcentrifugal flow components and flow components directed against ahousing are present, in which the flow components directed against thehousing serve primarily for the non-contact mounting and stabilising ofthe rotor in the housing. However, with an arrangement of the rotor atthe distal end of a catheter, a closed housing can not be readilyrealised with regard to flow technology, because such housing walls mustin fact lie at a precisely defined distance from the rotor, which,however, is not readily guaranteed at the distal end of a catheter.However, for the desired conveying capacity with the axial pumpaccording to the invention, provision is also made according to theinvention that the rotor has guide surfaces to produce centrifugal flowcomponents.

The driving fluid can be used within the scope of the invention in orderto be able to operate a balloon for retroperfusion. The embodiment ispreferably devised hereby so that the lumina for the driving fluid areguided through an expandable balloon surrounding the catheter in asealing manner, and that the lumina have separately controllable closuremembers via which driving fluid can arrive in the balloon or out of theballoon into the respective lumina, in which preferably the closuremembers are formed as magneto valves. On inflation of the balloon,additional driving medium is required which can be discharged again oncollapsing of the balloon. This is possible extracorporally on the driveside by means of a reservoir.

The embodiment to assist the performance of a heart according to theinvention, in which fluid is conveyed in blood vessels with the use of apump and the conveyed quantity is able to be regulated as a function ofmeasurement values of a heart ventricle catheter, from which the cardiacoutput is determined, proceeds from a development according to AT 407960 B and is characterised substantially in that the pump is formed asan intravasal rotary pump at the periphery or at the distal end of thecatheter, the rotor of which, lying on the outside, is connected via amagneto coupling with the drive which is arranged inside the catheter.

BRIEF DESCRIPTION OF DRAWINGS

The invention is explained in further detail below by use of anexemplary embodiment which is illustrated diagrammatically in thedrawings, in which

FIG. 1 shows a diagrammatic illustration of the arrangement of the pumpand of the drive,

FIG. 2 shows a diagrammatic illustration of the distal end of a catheterwhich is used according to the invention, and

FIG. 3 shows an enlarged illustration of the part of the catheterbearing the balloon, in section.

DETAILED DESCRIPTION

In FIG. 1, a heart is designated by 1, into which a heart ventriclecatheter 2 is introduced. The catheter is introduced here for examplevia the femoral artery and the aortic arch 3 into the heart chamber andcarries a series of sensors 4 via which the volume can be determined.The measurement signals are passed to a control arrangement 5. The heartventricle catheter is formed with several lumina, as additionallyillustrated below in further figures of the drawings, with fluid beingsupplied via such lumina to drive a rotor, arranged at the distal end,which forms the pump to assist the blood circulation and is designatedby 6 in FIG. 1. The positioning of this rotor is indicated in FIG. 1 bythe arrow 8. The driving medium for the rotor or the pump is guided in acircular flow by means of a fluid pump 7 which can be regulated in asynchronised manner as a function of the control signals generated inthe control arrangement 5. The distal region in which the pump isarranged is designated diagrammatically by 8, the catheter 2 having atits distal end a tube 9 leading to the suction end 10. A reservoir fordriving fluid is designated by 11, which provides additional drivingmedium for filling the balloon 12 serving for an occlusion of theartery, and which receives again the volume of driving medium occurringon deflation of the balloon.

The volumetric measurement in the cardiac chamber allows differences tobe reliably detected between the diastolic and systolic volume andallows corresponding correction signals to be made available for theoutput of the synchronised fluid pump 7. Furthermore, in the controlcircuit 5, corresponding fixed values can be provided, such as forexample a defined cardiac output, which is referred to on deviation ofthe measured cardiac output to control the pump.

A retroperfusion can take place via a conventional balloon catheterwhich is occluded in a correspondingly synchronised manner, so that thedirected return is in fact guaranteed during the diastole. Hereby thecorresponding measurement values for the heart rate or for the correctmoment of the diastole can be obtained from ECG data.

In FIG. 2, the distal end of a modified catheter 2 is now illustrated.The end side 13 of this catheter has two pocket-shaped chambers 14 and15, in which bar magnets are respectively arranged. The bar magnet 16 isconnected here at the distal end outwards via a shaft 17 with a rotor18, whereas the bar magnet 19 lying on the inside is connected via ashaft 20 with a drive wheel 21. The drive wheel 21 is formed here as apaddle wheel and is acted upon with fluid via a lumen 22, this fluidflowing off again via the lumen 23 of the catheter. The rotation of thepaddle wheel 21 is regulated here accordingly by corresponding controlof the fluid pressure in the lumen 22 serving for the supply of fluid,in which the magnet 19, which is connected so as to be locked againstrelative rotation with the paddle wheel 21, is set into correspondingrotation. At the outer side, which is completely sealed with respect tothe lumina 22 and 23, the magnet 16 is subsequently entrainedaccordingly and drives the rotor 18 via the shaft 17, whereby a flow isformed in the region of the tube 9, as is indicated by the arrows 24,and which assists the natural blood flow in the vessel 26, illustratedby the arrow 25.

In FIG. 3, the partial region of the balloon 12, which is connected in asealing manner to the catheter 2, is illustrated on an enlarged scale.The two lumina leading away from the fluid pump 7 and back to the fluidpump 7 are designated in turn by 22 and 23. In the region of the balloon12, the wall of these lumina is provided with valves which can beactuated magnetically for example. The valves are indicateddiagrammatically by 27 and 28. An opening of the valve 27 leads to thefluid, coming from the fluid pump 7, which is under pressure, which isindicated by the “+” sign, being pumped into the balloon 12, with whichthe overall quantity of the circulating driving fluid would of course bereduced, in so far as the reservoir 11, indicated diagrammatically inFIG. 1, is not provided. By closing the valve 27, the occlusion isclosed off, the collapsing of the balloon 12 being able to be broughtabout by opening the valve 28 and the fluid now being drawn off via thelumen 23, leading back to the pump, which lumen 23 is at a slightlylower pressure which is indicated by the “−” sign. As the overall volumeof the fluid in the circulating system is now to be reduced, a portionof this volume must be pumped back again into the reservoir 11 accordingto FIG. 1.

1. A catheter to assist a performance of a heart, comprising: at leastone pump, wherein the pump is formed as a rotary pump arranged at adistal end of the catheter, a rotor of said pump being arranged distallyat an outer side of said catheter, and being coupled with a drive wheelvia a magneto coupling, said drive wheel arranged inside the catheterand formed as a hydraulically or pneumatically operated paddle wheel; afirst lumen of the catheter supplying driving fluid to the drive wheel;and a second lumen of the catheter carrying off driving fluid from thedrive wheel, wherein said first lumen and second lumen for the drivingfluid are guided through an expandable balloon surrounding the catheterin a sealing manner, and said first lumen and second lumen each carryseparately controllable closure members via which driving fluid movesinto the balloon or moves out of the balloon into the respective firstlumen and second lumen.
 2. Catheter according to claim 1, wherein thedrive wheel comprises axial or semi-axial blades.
 3. Catheter accordingto claim 2, wherein an axis of rotation of the rotor is in alignmentwith a longitudinal axis of the catheter, or is parallel thereto. 4.Catheter according to claim 2, wherein the magneto coupling is formed ofbar magnets, said bar magnets being arranged in adjacent chambers,separated from each other by a sealing wall, at the distal end of thecatheter, a first one of said bar magnets is connected with the rotor soas to be locked against relative rotation with respect to the rotor, anda second one of said bar magnets is connected with the drive wheel so asto be locked against relative rotation with respect to the drive wheel.5. The catheter according to claim 2, wherein the rotor comprises guidesurfaces to produce centrifugal flow components.
 6. Catheter accordingto claim 1, wherein an axis of rotation of the rotor is in alignmentwith a longitudinal axis of the catheter, or is parallel thereto. 7.Catheter according to claim 6, wherein the magneto coupling is formed ofbar magnets, said bar magnets being arranged in adjacent chambers,separated from each other by a sealing wall, at the distal end of thecatheter, a first one of said bar magnets is connected with the rotor soas to be locked against relative rotation with respect to the rotor, anda second one of said bar magnets is connected with the drive wheel so asto be locked against relative rotation with respect to the drive wheel.8. The catheter according to claim 6, wherein the rotor comprises guidesurfaces to produce centrifugal flow components.
 9. Catheter accordingto claim 1, wherein the magneto coupling is formed of bar magnets, saidbar magnets being arranged in adjacent chambers, separated from eachother by a sealing wall, at the distal end of the catheter, a first oneof said bar magnets is connected with the rotor so as to be lockedagainst relative rotation with respect to the rotor, and a second one ofsaid bar magnets is connected with the drive wheel so as to be lockedagainst relative rotation with respect to the drive wheel.
 10. Catheteraccording to claim 9, wherein a first connection between said first barmagnet and the rotor is mounted in a wall of its respective chamberfacing away from the sealing wall and facing toward the rotor, and asecond connection between said second bar magnet and the drive wheel ismounted in a wall of its respective chamber facing away from the sealingwall and facing toward the drive wheel.
 11. The catheter according toclaim 10, wherein the rotor comprises guide surfaces to producecentrifugal flow components.
 12. The catheter according to claim 9,wherein the rotor comprises guide surfaces to produce centrifugal flowcomponents.
 13. The catheter according to claim 1, wherein the rotorcomprises guide surfaces to produce centrifugal flow components.
 14. Thecatheter according to claim 1, wherein the closure members are formed asmagneto valves.